EAP Key Derivation For Multiple Application - PowerPoint PPT Presentation

EAP Key Derivation For Multiple Application (draft-salowey-eap-key-deriv-00.txt) Pasi Eronen (pasi.eronen@nokia.com) Joe Salowey (jsalowey@cisco.com)

Motivation • Key Material needed for multiple applications • Independent of EAP-Mech • Independent of Applications • Cryptographic Separation between apps • Consistent Key Derivation

Applications • Link Layer Ciphering (WEP,802.11i,MPPE,…) • Fast Roaming • Re-Authentication • Message Protection • Things we have not thought of yet!

Requirements • Reserve/Specify Extended Master Session Key Material (EMSK) (draft-aboba-pppext-key-problem-06.txt) – Not enough alone, No guarantee that applications will derive independent keys. – Cryptographic separation and EMSK security left to chance • Standard KDF to derive application specific master session keys (AMSK) from EMSK

Key Derivation • Use labeled key derivation (e.g. TLS PRF) – Label = string (“application name and key use”) – May include application specific data • Application – Registers key label (with IANA) – Defines how keys will be used/derived from (AMSK) – Defines where keys are used and how they get there • Independent Keys are derived for each application

Issues • How much material should be reserved for EMSK? • EMSK stays within EAP-Server • Binding of multiple keys

Questions? • http://www.ietf.org/internet-drafts/draft- salowey-eap-key-deriv-00.txt jsalowey@cisco.com pasi.eronen@nokia.com